python check global variable exists

To check the existence of a local variable:

if 'myVar' in locals():
  # myVar exists.

To check the existence of a global variable:

if 'myVar' in globals():
  # myVar exists.

To check if an object has an attribute:

if hasattr(obj, 'attr_name'):
  # obj.attr_name exists.

資料來源: How do I check if a variable exists?
https://stackoverflow.com/questions/843277/how-do-i-check-if-a-variable-exists